Progress in Crystal Growth and Characterization of Materials最新文献

Low dimensional structures, including bulk crystals, thin films, nanowires and nanotubes, have received remarkable attention due to their novel functionality and potential applications in various areas of optics, electronics, photonics, and sensing devices and photovoltaic field. Recently, remarkable progress and modification have been achieved in the synthesis process of crystalline material by vapor transport technique. In this review, we introduce an improved concept of the closed tube Chemical Vapor Transport (CVT) technique for the single crystal growth of ZrSTe, TiSTe and TiSeTe. A modified reverse temperature profile has reported the growth of ZrSTe, TiSTe and TiSeTe results show the good crystalline quality of synthesized materials. The single-crystal X-ray diffraction data reveals all three samples have trigonal unit cell structure with a space group of P31. The Semiconducting behavior of grown crystals of ZrSTe, TiSTe and TiSeTe was verified by two probe resistivity measurements, Hall Effect measurements and optical absorption at room temperature in the spectral range of 200 nm - 2200 nm. In this review, we highlight the recent progress in the transition of metal chalcogenides for their advanced application in solar energy conversion, thin-film electronics, optoelectronic devices and quantum communication devices. Moreover, different experimental challenges within the described growth technique are probed. Additionally, a survey was done for the possible enhancement of Transition Metal Chalcogenide (TMC) crystalline materials grown by the Chemical Vapor Transport technique based on various growth parameters.

As known currently, in the formation of the Earth, minerals have played a pivotal role going from the formation of the hydrosphere, the lithosphere, and all Earth components until the origin, evolution, and maintenance of life. The first signs of magnetism are found in komatiites. In the origin of life, minerals were responsible for concentrating, aligning, and acting as templates and catalyzers, allowing for the formation of bonds among the first biomolecules to form polymers, which eventually became assembled to give rise to the pioneer organism in the Precambrian. Besides, minerals allowed the DNA to be the information storing molecule, even though it was not the first biomolecule. Another function of minerals was to protect the organic complexes against ultraviolet radiation and hydrolysis, a fundamental action to preserve life in the Precambrian where high UV radiation prevailed. Minerals not only favored the origin of life but also became part of the organisms that inhabit the Earth, including species of the five kingdoms, comprising from microorganisms to higher organisms. How minerals participated in the origin of life still has unresolved questions, for which to understand the minerals’ participation since the formation of the Earth until becoming part of the structure of organisms from the five kingdoms, we reviewed the following topics, which will contribute to the understanding of the implication of minerals in the origin of our planet and life on it: i) the synthesis of the chemical elements from which the first mineral were obtained in the Earth, ii) the factor that favored the formation of minerals in the Earth, iii) the implication of minerals as the basis for the synthesis of the first biomolecule and, eventually, the pioneer organism, as well as the biomineralization mechanism that has been proposed to account for the mineral part contained in the structure of the organisms from the different kingdoms, and iv) the models that allow emulating the mechanisms by which minerals participated in the synthesis of the first biomolecule; in this way, for example, the Precambrian microfossils are so simple morphologically (spheres, subspheres, and hemispheres) that they can easily be imitated by hollow mineral growths, known as biomorphs. Although these can interfere with the study of actual microfossils, they remain as key points for the study of the origin of life.

This contribution deals with a practical overview of some popular and sophisticated crystallization methods that help increase the success rate of a crystallization project and introduces a newly developed method involving low intensity electromagnetic fields. Aiming to suggest a methodology to follow, the present contribution is divided into two main parts in a logical order to get the best crystals for high resolution X-ray crystallographic analysis. The first part starts with a short review of the chemical and physical fundamentals of each crystallization method through different strategies based on physicochemical approaches. Then, practical non-conventional techniques for protein crystallization are presented, not only for growing protein crystals, but also for controlling the size and number of crystals. These include crystal growth in gels, counter-diffusion, seeding, and macromolecular imprinted polymers (MIPs). The second part shows the effects of coupling low intensity electric fields (in the scale of units of  μAmperes) with weak magnetic fields (in the scale of milli Tesla) applied to protein crystallization. This approach consists of a novel experimental set up, which was used to study the influence of the coupled fields on the crystallization of lysozyme in solution and in gel media. This new approach is based on the classical theories of transport phenomena and offers a more accessible strategy to obtain suitable crystals for X-ray characterization or Neutron diffraction investigations.

Ice is one of the most abundant materials on the earth's surface, and its growth governs various natural phenomena. Hence, the molecular-level understanding of ice crystal surfaces is crucially important. However, it is generally acknowledged that the molecular-level observation of ice crystal surfaces by ordinary microscopy techniques, such as atomic force microscopy and scanning electron microscopy, is very difficult at temperatures near the melting point (0 °C). To overcome such difficulties, we have developed laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM). We proved that LCM-DIM can visualize individual elementary steps (0.37 nm in thickness) on a basal face by observing two-dimensional nucleation growth. Then we found by LCM-DIM that spiral steps on a basal face exhibit a double-spiral pattern, which can be expected from ice's crystallographic structure. In addition, we revealed that temperature dependence of growth kinetics of elementary spiral steps on a basal face exhibits complicated behaviors, which show the presence of unknown phenomena in the growth kinetics. Furthermore, we proved that surface diffusion of water admolecules on a basal face plays a crucially important role in the lateral growth of elementary steps when the distance between adjacent spiral steps is smaller than 15 µm. These findings will provide a clue for unlocking growth kinetics of ice crystals. In addition, through the use of LCM-DIM much progress has been made in studies on the surface melting of ice and the interaction between ice and atmospheric gasses.

In recent years, a series of investigations has been devoted to a possibility of using crystals based on CdTe with addition of magnesium (Mg), selenium (Se), or manganese (Mn) for X and gamma radiation detectors. In the literature there are contradictory data with respect to the segregation of Mg in (Cd,Mg)Te and Se in Cd(Te,Se) and to the possibility of obtaining materials with a homogeneous composition without grains and twins.

We have wide technological possibilities of preparing crystals and investigating some of their properties. Thus, we performed crystallizations of (Cd,Mg)Te, Cd(Te,Se), (Cd,Mn)(Te,Se), and (Cd,Mn)Te compounds. The aim of our studies was to check whether any of the investigated materials may be easily obtained by the Low Pressure Bridgman (LPB) method in the form of large, homogeneous, high resistivity single crystals with as few as possible twins, subgrains, and tellurium inclusions.

The crystallization processes were performed by using the LPB method. The elements used: Cd, Te, Mn, Mg, and Se were of the highest purity available at that time. In order to obtain reliable conclusions the crystallization processes were carried out under identical technological conditions. The details of our technological method and the results of the investigation of physical properties of the samples are presented below.

This review paper covers the low temperature wet growth of nano-engineered particles of ZnO-based mixed metal oxides, their growth mechanism, and characterization using X-ray diffraction, SEM, TEM and IR, UV–visible, and XPS spectral techniques. Main focus of this article is centered on low temperature semi-wet methods of synthesis that are suitable for large scale production of zinc oxide-based systems mixed with iron oxide, copper oxide, nickel oxide and cobalt oxide. These mixed metal oxides have broad industrial applications as catalyst, semiconductors, adsorbents, superconductors, electro-ceramics, and antifungal agents in addition to extensive applications in medicines. This paper discusses the low-cost and environment friendly synthesis of these mixed metal oxides, measurement of properties and applicability of these materials systems.

Graphitic carbon nanoparticles are in high demand for sensing, health care, and manufacturing industries. Physical vapour deposition (PVD) methods are advantageous for in-situ synthesis of graphitic carbon particles due to their ability to produce large area distributions. However, the carbon particles can agglomerate, irrespective of the PVD method, and form coagulated structures while growing inside the vacuum chamber. The random shapes and sizes of these particles lead to non-uniform properties and characteristics, hence making them less attractive for numerous industrial applications, such as energy storage batteries and structural health monitoring. Therefore, the in-situ synthesis of isolated carbon particles produced in a single-step PVD process having control over size, shape, and large area distributions has remained inspiring for the past 30 years. This article gives an overview of characteristics, applications, industrial impact, and global revenue of graphite particles. A critical review on in-situ growth of graphitic carbon particles with different PVD methods is described with selected examples. A comprehensive summary compares the capability of different PVD techniques and corresponding carbon resources to produce graphitic particles with numerous sizes and shapes. Analysing the outputs of various PVD methods, a generalised four-stage model is explained to understand the in-situ growth of graphitic carbon particles, which start from seedings and grow as particles, clusters, and granular structures. It is concluded that the isolated carbon particles can be produced with specific size, shape, and distributions irrespective of the PVD method employed, by maintaining precise control over combinations of deposition system properties and process parameters.